Getting to the Nuts & and Bolts

The Work Breakdown Structure.

In my earlier posts I started to describe all the fundamental organization necessary to use an Earned Value method for performance measurement. I wanted to describe a way to measure how well a team performs using a quantitative method that accurately portrays the team’s efforts. Let’s begin by defining the work that needs to be done using the grand daddy of all work structures, the Work Breakdown Structure or WBS.

The organization of the project defines the entire contractual scope of the work. A Work Breakdown Structure (WBS) defines the work plus it helps identify the tasks associated with the work. The WBS is the vehicle which also helps define the relationships between tasks and the Control Accounts (CAs) used to budget the tasks being performed. A WBS is a product oriented hierarchical tree which defines the division of goods and services. Think of it as a family tree of the effort that is defined by the statement of work (SOW). The WBS has all the contractually agreed to scope of the project, and it permits the PM the ability to define the scope at various logical levels of manageable segments and elements of work.

The WBS begins at the level one (1) or head of the tree, and then in descending order begins to logically define the scope of work to be performed. At each step additional lower levels of detail are added to further delineate and define the work that needs to be done. Table 1 depicts a WBS structure for the fictitious home construction company. In this case the work to be performed is to create a new home from scratch, and the WBS describes the scope and tasks associated with the work to be performed.

Table 1. A WBS for a fictitious home construction company

Notice that the WBS doesn’t describe the organizational aspect of the company. The WBS doesn’t tell the PM which groups or organizations do the work. The WBS does however show the hierarchy of how the work on the product will be executed. It includes all of the work that has to be performed, and each element below the top element provides enough detail that stakeholders can differentiate where the work is done by task. Notice that the WBS is not resources oriented and doesn’t offer a bill of material on what the house requires to be built.

Another aspect of the WBS worth noting is that starting with the top-tier, or level one, each subsequent element in the WBS structure has an increasing level of detail. Looking once more at table 1, the top-tier is the name of project. The second level tier in the hierarchy describes the first task of the project, and can describe major activities. The third tier (or level three) describes a breakdown of concrete pouring tasks for example and other activities. Each subsequent tier or level describes in ever-increasing detail the scope of the work being performed. Theoretically each level below can also describe in ever infinite detail more information until it is impracticable to delineate the work further. Other WBS structures exists for various types of work, and industries. Here are two links showing examples of an aircraft WBS structure:

There are many ways to develop a good WBS however the PM must always keep in mind that the WBS must incorporate and reflect all the approved and contracted project scope. The WBS must reflect how the PM is going to manage the project, and may be provided by the customer in the statement of work. Other considerations for the PM include:

The size of the project

The complexity of the project

The resources and types of resources on the project (internal vs. contracted help)

Reporting requirements (if any) of the project

Armed with this information the PM will gather the various disciplines from the organizations participating in the project and create the Work Breakdown Structure Dictionary or WBS Dictionary.

The WBS Dictionary is a document which describes the work that is in scope, and more importantly the work that’s not in scope by the various WBS elements. When projects are complex the PM will need to make sure the proper communication and understanding of the scope of work is accepted. The one document that defines each element of the WBS is the WBS dictionary. It is an effective tool for ensuring that the project is well executed. The dictionary is used to describe the work at the level in the WBS it’s being performed, and the deliverable.

By defining each element in the WBS, the PM can identify which tasks are closely related to each other. Those items that are not related are segregated and properly identified so that they can be related to the correct elements if they are in scope. The WBS dictionary also permits the PM the opportunity to document a scope baseline such that when the project commences, any change in scope is understood using this document.